Phase noise and waveform damage caused by intra-channel nonlinearity are one of the sources leading to cost of a long-haul transmission optical communication system. In a coherent optical communication system, digital pre-distortion (DPD) of a transmitter (document of L. Dou et al, OFC2011, paper OThF5) or digital Back-propagation (DBP) of a receiver (document of W. Yan et al., ECOC2011, paper Tu.3.A.2) may be used to compensate for the intra-channel nonlinearity damage.
In the implementation of the present invention, the inventors found that the ideas of these methods are focused on the calculation of nonlinearity damage of the whole or part of the channel, and the nonlinearity damage is eliminated by an operation of subtraction or phase modulation. Hence, there exists a problem of low performance due to incorrect calculation.
It should be noted that the above introduction to the background art is given for the clear and complete description of the technical solution of the present invention and for the understanding by those skilled in the art. The above technical solutions should not be deemed as being known to those skilled in the art for having been described in the background art of the present invention.